Lateralization of amygdala activation in fMRI may depend on phase-encoding polarity.

OBJECT

Susceptibility artifacts along the phase-encoding (PE) direction impact the activation pattern in the amygdala and may lead to systematic asymmetries. We implemented a triple-echo echo-planar imaging (EPI) sequence, acquiring opposite PE polarities along left-right PE direction in a single shot, to investigate its effects on amygdala lateralization.

MATERIALS AND METHODS

Twelve subjects viewed emotional faces to evoke amygdala activation.

RESULTS AND CONCLUSION

A region of interest analysis revealed that the lateralization of amygdala responses depended on the PE polarity thus representing a pure method artifact. Alternating PE with multi-echo EPI reduced the artifact. Lateralized fMRI activation in areas with magnetic field inhomogeneities need to be interpreted with caution.